Extracorporeal blood chamber

ABSTRACT

An extracorporeal blood chamber ( 12 ) comprises an expansion reservoir ( 47 ) having a first access ( 48 ) arranged laterally and a second access ( 49 ) arranged on the bottom of the chamber ( 12 ). The chamber comprises, integrally with the reservoir, a first conduit terminating in the first access, a second conduit terminating in the first access, and a third conduit terminating in the second access. The extracorporeal blood enters the reservoir through the first conduit and there mixes with an infusion fluid which enters through the second conduit. The resulting mixture exits through the third conduit. The chamber is used in a hemo(dia)filtration apparatus to mix the blood optimally with the replacement fluid.

BACKGROUND OF THE INVENTION

The invention relates to an extracorporeal blood chamber, to anextracorporeal blood line and to an apparatus for treatment ofextracorporeal blood.

In particular the extracorporeal blood chamber is for air/liquidseparation and/or for the mixing of two liquids, for example blood andan infusion liquid.

Specifically, though not exclusively, the invention can be usefullyapplied in a hemo(dia)filtration system for mixing extracorporeal bloodwith a replacement fluid.

U.S. Pat. No. 5,605,540 describes an extracorporeal blood chamberprovided with an expansion chamber having on a bottom thereof a firstand a second access and at the top thereof at least a third access; theblood chamber is further provided with a first and a second conduit,terminating respectively in the first and second accesses, and with athird conduit terminating in the first conduit. In use the first and thesecond conduit transport blood, while the third conduit transports aninfusion liquid.

U.S. Pat. No. 4,681,606 describes an extracorporeal blood chamberprovided with an expansion chamber having at a bottom thereof a firstaccess, on a side thereof a second access, and at a top thereof twofurther accesses; the blood chamber also has a first and a secondconduit terminating respectively in the first and the second access. Inuse the first and the second conduit transport blood, while one of thetop accesses is connected to an injection tube.

U.S. Pat. No. 5,591,251 describes an extracorporeal blood chamberprovided with an expansion chamber having at a bottom thereof a firstaccess, on a side thereof a second access, and at a top thereof anothertwo accesses; the blood chamber further has a conduit terminating in thefirst lateral access. In use the first and the second access are for thepassage of blood, while one of the top accesses is for passage of aninfusion liquid.

U.S. Pat. No. 4,666,598 describes an extracorporeal blood chamberprovided with an expansion chamber having on a bottom thereof a firstaccess and on a side thereof a second access; the blood chamber also hasa first conduit terminating in the first access, a second conduitterminating in the second access, and a third conduit terminating in thefirst conduit. In use the first and the second conduits transport blood,while the third conduit transports an infusion liquid.

The prior-art extracorporeal blood chambers can be improved upon inrelation to the effectiveness of the mixing between the blood and theinfusion liquid, especially in the case of a hemo(dia)filtrationtreatment with mixing between the blood and the replacement liquidupstream of the hemo(dia)filter (pre-dilution). In a case ofpre-dilution the effectiveness of the hemo(dia)filtration treatmentdepends on the degree of mixing between the blood and the replacementliquid at the inlet of the hemo(dia)filter.

SUMMARY OF THE INVENTION

An aim of the present invention is to provide an extracorporeal bloodchamber with which very good mixing results of the blood with aninfusion liquid can be obtained.

A further aim of the invention is to realise an extracorporeal bloodline comprising the above-mentioned blood chamber.

A further aim of the invention is to provide an apparatus forextracorporeal blood treatment comprising the above-cited blood line.

An advantage of the invention is that it provides an extracorporealblood chamber which is able efficiently to separate the air from theliquid, in particular the air contained in the infusion liquid.

A further advantage is that it makes available an extracorporeal bloodchamber which reduces to a minimum the turbulence in the blood flow inthe case of absence of infusion liquid flow, i.e. when the blood is notmixed with the liquid.

A still further advantage is that the extracorporeal blood chamber iscompact and small.

The aims and more besides are all attained by the invention, as it ischaracterised in one or more of the appended claims.

Further characteristics and advantages of the present invention willbetter emerge from the detailed description that follows, of at least anembodiment of the invention, illustrated by way of non-limiting examplein the figures of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description will be made herein below with reference to the appendedfigures of the drawings, provided by way of non-limiting example, inwhich:

FIG. 1 is a diagram of the hemo(dia)filtration apparatus of theinvention;

FIG. 2 is a front view of an apparatus made according to the diagram ofFIG. 1, and applied operatively to the front panel of a machine fordialysis;

FIG. 3 is a perspective view from behind of the apparatus of FIG. 2,with some parts removed better to evidence others;

FIG. 4 is a perspective view from the front of FIG. 3;

FIG. 5 is a perspective view from behind of the infusion module of theapparatus of FIG. 3, with some parts removed and other parts added withrespect to FIG. 3;

FIG. 6 is a view from the front of FIG. 5;

FIG. 7 is a front view of a component of the infusion module of FIG. 3which includes the blood chamber 12 in which the mixing between theblood and the infused liquid takes place;

FIG. 8 is a view from behind of FIG. 7;

FIG. 9 is a view from above of FIG. 7;

FIG. 10 is a view from below of FIG. 7;

FIG. 11 is a view from the left of FIG. 7;

FIGS. 12, 13, 14 and 15 are sections according respectively to linesXII, XIII, XIV and XV of FIGS. 7, 8 and 11.

DETAILED DESCRIPTION

With reference to FIG. 1, 1 denotes in its entirety an extracorporealblood treatment apparatus destined for coupling to a machine is forextracorporeal blood treatment able to provide a treatment fluid. In thefollowing description the extracorporeal blood treatment apparatus willbe called a hemo(dia)filtration apparatus 1, the extracorporeal bloodtreatment machine will be called a dialysis machine and the treatmentfluid will be called dialysis fluid, without any more generalisedreferences being lost by use of this terminology. In particular thedialysis machine produces on-line a dialysis fluid of predeterminedchemical composition (for example by mixing water and solid and/orliquid concentrates). The dialysis machine is able to reduce theconcentration of endotoxins in the dialysis fluid (for example bypassage of dialysis fluid through one or more stages ofultrafiltration). The dialysis machine is able to provide a controlsystem of patient weight loss during the treatment (for example by acontrol of the difference between the dialysis fluid delivery at theinlet and outlet of the blood treatment device thanks to the use of twopumps arranged before and after the blood treatment device—hereinafterhemo(dia)filter—and of two flow-meters arranged before and after thehemo(dia)filter). The hemo(dia)filtration apparatus 1 can be composed,all or in part, by disposable elements. The dialysis machine (of whichthe front panel is partially illustrated in FIG. 2) is of known type, isprovided with a fresh dialyser fluid port 2 (see the diagram of FIG. 1),from which the dialysis fluid to be introduced in the hemo(dia) filteris taken, an exhausted fluid port 3, in which the fluid exiting thehemo(dia)filter is discharged (made up of used dialysis fluid and/or ofultrafiltrate), and an on-line port 4 from which the dialysis fluid, tobe processed for use as replacement fluid in hemo(dia)filtrationtreatment, is taken. The dialysis machine is further provided with asystem of known type and not illustrated, for preparation of thedialysis fluid; this system is connected to a main dialysis fluid supplyline, which terminates in the fresh dialysate port 2. A secondarydialysis fluid supply line, which branches from the main supply line,terminates in the on-line port 4. The dialysis machine is furtherprovided with an exhausted liquid discharge line which originates at oneend at the exhausted liquid port 3 and which terminates at the other endthereof in a drainage (of known type and not illustrated). When thehemo(dia)filtration apparatus 1 is used as a hemofiltration apparatus 1,the fresh dialysate port 2 is closed, or non-operative, or, in a furtherembodiment, absent.

The hemo(dia)filtration apparatus 1 comprises the hemo(dia)filter 5having a blood chamber and a fluid chamber (not illustrated) which areseparated from one another by a semipermeable membrane (not illustrated)which, in this case, comprises a bundle of hollow fibres. In thisembodiment the blood chamber comprises the space internally of thehollow fibres, while the fluid chamber comprises the space externally ofthe hollow fibres. The fluid chamber is further at least partiallydefined by the tubular body containing the bundle of hollow fibres. Thehemo(dia)filtration apparatus 1 comprises an extracorporeal bloodcircuit having an arterial line 6, or a blood removal line from thepatient for the blood to be treated in the hemo(dia)filter 5, and avenous line 7, or patient return line for the blood treated in thehemo(dia)filter 5. The hemo(dia)filtration apparatus 1 further comprisesa blood pump 8 for circulation of blood in the extracorporeal circuit.The blood pump 8 is of a tube-deforming rotary type (peristaltic). Theextracorporeal blood circuit further comprises the blood chamber of thehemo(dia)filter 5. The arterial line 6 comprises an arterial patient end9, a pre-pump arterial expansion chamber 10, a blood pump tube tract 11,a post-pump arterial expansion chamber 12, an arterial device end 13.The venous line 7 comprises a venous device end 14, a venous expansionchamber 15, a venous patient end 16. The dialysis machine is providedwith an arterial clamp 17 operating on the arterial line 6, inparticular between the patient arterial end 9 and the pre-pump arterialexpansion chamber 10. The dialysis machine is provided with a venousclamp 18 operating on the venous line 7, in particular between thepatient venous end 16 and the venous expansion chamber 15. The patientarterial end 9, like the patient venous end 16, is designed forconnection (directly or via a vascular access device of known type) witha vascular access of a patient. The arterial clamp 17, respectively thevenous clamp 18, serves for closing a squeezable tract of the arterialline 6, respectively of the venous line 7, on command of a control unitof the dialysis machine. The pre-pump arterial expansion chamber 10,which is arranged downstream of the arterial clamp 17 (where“downstream” means with reference to the blood circulation directionduring the treatment), serves for separating the air contained in theblood and for monitoring the arterial blood pressure (before the bloodpump 8). The venous expansion chamber 15, which is arranged upstream ofthe venous clamp 18 (where “upstream” means with reference to the bloodcirculation direction during the treatment), is for separating the aircontained in the blood and for monitoring the venous blood pressure. Thepre-pump arterial expansion chamber 10, like the venous expansionchamber 15, is designed to give rise to a liquid level separating alower part full of liquid (blood) from an upper part full of gas (air).Each of the expansion chambers 10 and 15 is provided, for examplesuperiorly, with a zone predisposed for pressure reading; this zonecomprises, in the specific case, a membrane device, of known type,having a deformable elastic membrane with an internal surface in contactwith the fluid (blood and/or air) contained in the chamber and anexternal surface operatively associable to a pressure sensor of thedialysis machine. The blood pump tube tract 11, which is designed forremovably coupling with the blood pump 8, is open-ring conformed (in thespecific embodiment it is U-shaped with a horizontal lie and with theconvexity facing right, with reference to the viewpoint of a usersituated in front of the front panel of the dialysis machine) with twoends, one for blood inlet and the other for blood outlet, fluidly andmechanically connected to two tubular extensions 19 (FIG. 2) solidlyconnected to the pre-pump arterial expansion chamber 10. The arterialdevice end 13 and the venous device end 14 are designed for removablycoupling with an inlet port (in the specific embodiment, upper) and,respectively, an outlet port (in the specific embodiment, lower) of theblood chamber of the hemo(dia)filter 5. The pre-pump arterial expansionchamber 10 and the venous expansion chamber 15 are integrated in acartridge structure of known type.

The post-pump arterial expansion chamber 12 is inserted in the arterialline 6 between the blood pump 8 and the hemo(dia)filter 5. The post-pumparterial expansion chamber 12 comprises a blood inlet port 20, aninfusion fluid inlet port 21 (in the present example ofhemo(dia)filtration with pre-dilution, the infusion fluid, or infusate,can be replacement fluid, or substituate; in the following descriptionthe specific term “replacement fluid” and “substituate” will be usedinstead of more general terms like “infusion fluid” and “infusate”,without the generalised meaning being compromised), a mixing zone wherethe blood and replacement fluid are mixed, and an outlet port for theblood-fluid mixture 22 (where the replacement fluid is present in themixture in case of pre-dilution and absent in case of no pre-dilution).

The post-pump arterial expansion chamber 12 serves to separate the aircontained in the replacement fluid. The post-pump arterial expansionchamber 12 monitors the pressure in the replacement fluid supply line.The post-pump arterial expansion chamber 12 also serves to furtherseparate the air contained in the blood along the arterial line 6downstream of the blood pump 8 and for monitoring the blood pressure inthe arterial line 6 between the blood pump and the hemo(dia)filter 5.The post-pump arterial expansion chamber 12 is designed to produce aliquid level that separates a lower part which is full of liquid (bloodor blood/replacement fluid mixture) and an upper part which is full ofgas (air). The post-pump arterial expansion chamber 12 is provided, forexample superiorly, with a zone predisposed for pressure detection; thiszone comprises, in the present embodiment, a membrane device 58, ofknown type, having a deformable membrane with an internal surface incontact with the fluid contained in the chamber and an external surfacewhich is operatively associable to a pressure sensor of the dialysismachine. The post-pump arterial expansion chamber 12 will be describedin greater detail herein below.

The hemo(dia)filtration apparatus 1 comprises a replacement fluid supplyline 23 which provides, in this embodiment, the replacement fluid(substituate) to the extracorporeal blood circuit. The supply line 23takes the dialysis fluid from the on-line port 4 and, after anultrafiltration treatment to make it suitable as a replacement fluid,conveys it to the extracorporeal blood circuit.

The supply line 23 branches out from a main branch 24 into apre-dilution branch 25 fluidly connected to the arterial line 6 and apost-dilution branch 26 fluidly connected to the venous line 7. Thereplacement fluid supply line 23 comprises an inlet end 27 having aconnector for removable connection with the on-line port 4 for sourcingthe dialysis fluid supplied by the dialysis machine. Alternatively to anon-line port of a machine for dialysis fluid preparation, other fluidsources can be used, for example a ready-prepared dialysis fluid orreplacement fluid recipient, or a centralised dialysis fluid supplysystem, supplying to various units.

The replacement fluid supply line 23 comprises an ultrafilter 28predisposed fluidly in the main branch 24 upstream of the branch-out forultrafiltering the dialysis fluid taken from the dialysis machine torender the fluid suitable for use as a replacement fluid. Theultrafilter 28 reduces the endotoxin percentage in the fluid. Theultrafilter 28 comprises a semipermeable membrane that separates a firstchamber containing the fluid to be ultrafiltered (dialysis fluid) from asecond chamber containing the ultrafiltered fluid (replacement fluid).The semipermeable membrane comprises, in the present embodiment, abundle of hollow fibres. The first chamber of the fluid to beultrafiltered comprises the inside of the hollow fibres, while thesecond chamber of the ultrafiltered fluid is defined between the outsideof the hollow fibres and the tubular body enclosing the bundle of hollowfibres.

The ultrafilter 28 is further provided, for example superiorly, with avent line of the air communicating with the first chamber of the fluidto be ultrafiltered and having a clamp (for example manually activated)for intercepting and a vent into the atmosphere protected by aprotection device (for example a hydrophobic membrane).

The replacement fluid supply line 23 can further comprise a check valvepredisposed fluidly in the main branch 24 upstream of the branch-out.The check valve, which in the present embodiment is not present, mightbe located after the ultrafilter 28.

A tract of the replacement fluid pump tube 29 is predisposed in thesupply line 23 for coupling with a replacement fluid circulation pump30. In to the present embodiment the replacement fluid pump 30 is atube-deforming rotary pump (peristaltic). The replacement fluid pumptube tract 29 is open-ring shaped with an aspiration end and a deliveryend. In particular the replacement fluid pump tube tract 29 is U-shaped,and, in the use configuration with the pump 30, lies on a verticalplane, with the two end branches arranged horizontally (the convexity ofthe U is directed oppositely to the blood pump tube tract 11, i.e. inthe present embodiment to the left with reference to the viewpoint of auser situated in front of the front panel of the machine). The rotationaxes of the two rotary pumps 8 and 30 are parallel to one another. Thepump tube tract 29, in the engaged configuration with the pump 30, isarranged symmetrically to the blood pump tube tract 11, with respect toa plane of symmetry (in the present embodiment, vertical) which isparallel to the rotation axes of the two rotary pumps 8 and 30. Thereplacement fluid pump tube tract 29 is fluidly arranged in the mainbranch 24 upstream of the branch-out (where “upstream” means inreference to the circulation direction of the replacement fluid). Thereplacement fluid pump tube tract 29 is arranged fluidly upstream of theultrafilter 28.

The replacement fluid supply line 23 comprises an auxiliary connection31 fluidly arranged after the ultrafilter 28. This auxiliary connection31 is branched out from the replacement fluid line 23. The auxiliaryline is further provided with a clamp 32 (for example a manuallyoperated clamp) for closing the auxiliary line, and a protection hoodfor removable closure of the auxiliary line 31. The auxiliary linebranches off from the main branch 24 before the branch-out.

The auxiliary connection 31 is designed for removable fluid connectionwith the extracorporeal blood circuit, in particular with the arterialline 6 or the venous line 7. The auxiliary connection 31 serves to fillthe extracorporeal circuit with the replacement fluid, in particularduring the circuit priming stage, i.e. during the stage preliminary tothe treatment during which the air and any other undesirable particlescontained in the blood circuit are evacuated and the circuit is filledwith an isotonic liquid, for example a saline solution coming from a bagor, as in the present embodiment, with an isotonic fluid (dialysis fluidor saline) which is prepared by the dialysis machine, supplied to theon-line port 4 of the machine and ultrafiltered by crossing thereplacement fluid supply line 23. In the present embodiment theauxiliary connection 31 is removably couplable to the patient end of thearterial line 9 or to the patient end of the venous line 16. Theauxiliary connection 31 comprises, for example, a female luer connectorcouplable to a is male luer connector at the patient arterial 9 orvenous 16 end.

At least one from among the three above-mentioned expansion chambers(arterial pre-pump 10, arterial post-pump 12 and venous 15) is fluidlyconnected, in particular directly, to the pre-dilution branch 25 or thepost-dilution branch 26. In the present embodiment the post-pumparterial expansion chamber 12 is fluidly connected directly to thepre-dilution branch 25.

The post-dilution branch 26 opens (directly) into a point of venous line7 comprised between the hemo(dia)filter 5 and the venous chamber 15. Thevenous chamber 15 therefore indirectly communicates, via a tract ofvenous line 7, with the post-dilution branch 26.

The aspiration and delivery ends of the replacement fluid pump tubetract 29 are rigidly connected to at least one from among theabove-mentioned expansion chambers (arterial pre-pump 10, arterialpost-pump 12 and venous 15). In the present embodiment the aspirationand delivery ends of the replacement fluid pump tube tract 29 areconnected rigidly to the post-pump arterial expansion chamber 12. Asmentioned, the expansion chamber bearing the replacement fluid pump tubetract 29, i.e. the chamber 12, is provided with a zone for monitoringthe pressure which is predisposed for connection with a pressure sensorprovided on the dialysis machine. This monitoring zone is provided withthe pressure detecting device 58.

Two tubular extensions for fluid and mechanical connection of the twoends of the pump tube tract 29 are solidly connected (for example aremade in a single piece with the chamber itself) to the chamber 12. Thetwo tubular extensions are not fluidly connected to the chamber 12, ifnot indirectly through other parts (for example the ultrafilter 28) ofthe fluid circuit transporting the replacement fluid.

The replacement fluid supply line 23 comprises a fluid communicationsystem which is interpositioned fluidly between the delivery end of thereplacement fluid pump tube tract 29 and the expansion chamber bearingthe replacement fluid pump tube tract 29 (as mentioned in this case theexpansion chamber bearing the pump tube tract 29 is the post-pumparterial expansion chamber 12). This fluid communication systemcomprises is one or more from the following elements: the ultrafilter28, the check valve (if present), the branch-out, and at least a tubetract which is flexible and closable by elastic deformation, inparticular squeezing.

In the present embodiment, the fluid communication system, which placesthe replacement fluid pump tube tract 29 in communication with theextracorporeal blood circuit, comprises a first flexible tube 41 havinga first end connected with a first tubular connection 42 which isrigidly connected to (but not fluidly communicating with) the post-pumparterial chamber 12 (the first tubular connection 42 is arrangedinferiorly of the chamber 12 itself), and a second end which is oppositethe first end and connected to a second tubular connection 43 for inletof the ultrafilter 28 (the second tubular connection 43 for inlet islocated inferiorly of the ultrafilter 28 and communicates with thechamber of the fluid to be ultrafiltered). Each of these tubularconnections 42 and 43 faces downwards, with reference to an operativeconfiguration of the apparatus 1. Each of these tubular connections 42and 43 has a longitudinal axis which extends, at least prevalently, in avertical direction.

The above-described fluid communication system comprises the ultrafilter28 and a second three-way flexible tube 44 having a first end which isconnected to a tubular connection for outlet of the ultrafilter 28 (thetubular outlet connection is located on a side of the ultrafilter 28itself, in particular superiorly, and communicates with theultrafiltrate fluid chamber, i.e. with the outside of the hollowfibres), a second end (arranged superiorly and facing upwards) to whichthe auxiliary connection 31 is connected by means of the auxiliary line,and a third end (arranged inferiorly and facing downwards).

The above-mentioned three ends of the second flexible tube 44 are inreciprocal fluid communication (for example with reciprocal T or Yarrangement). The second three-way flexible tube 44, which in thepresent embodiment is T-shaped with the first end arranged at 90° to theother two, is press-formed by injection of a soft plastic material.

The fluid communication system comprises a third three-way flexible tube45 having a first end which is connected to the third end of the secondflexible tube 44, a second end connected to the inlet port 21 of thereplacement fluid to the chamber 12, and a third end connected to a zoneof the venous line 7 arranged upstream of the venous expansion chamber15. In the present embodiment the first end is arranged superiorly(facing upwards), the third end is arranged inferiorly (facingdownwards), while the second end is arranged obliquely (facing upwards)with respect to the other two, forming an angle which is less than aright-angle with the first upper end. The third three-way flexible tube45 is made by press-forming by injection of a soft plastic material. Thethird three-way flexible tube 45 exhibits the branch-out in thepre-dilution branches 25 and the post-dilution branches 26, whichcomprise two of the three ways of the third flexible tube 45 (inparticular the ways that exhibit the second and third ends).

The hemodiafiltration apparatus 1 is made in two distinct modules whichare fluidly connected one to the other. A first module A (on the rightin FIG. 2) comprises an initial tract of arterial line 6 which goes fromthe patient arterial end 9 to the pre-pump expansion chamber 10. Thefirst module A further comprises the pre-pump expansion chamber 10, theblood pump tube tract 11 and the venous expansion chamber 15 (integratedwith the chamber 10 in the cartridge structure of known type). The firstmodule A further comprises a final tract of venous line 7 which goesfrom the venous expansion chamber 15 to the patient venous end 16. Thefirst module A also comprises a tract of arterial line 6 which isarranged downstream of the blood pump 8 and which is integrated into thecartridge body structure. As mentioned, the cartridge structure, whichincorporates the chambers 10 and 15, supports the two ends, aspirationand delivery, of the blood pump tube tract 11.

A second module B (on the left in FIG. 2) comprises the replacementfluid supply line 23 (starting from the inlet end 27, and including thereplacement fluid pump tube tract 29, the ultrafilter 28 and thepre-dilution and post-dilution branches 25 and 26). The second module Bfurther comprises the post-pump arterial expansion chamber 12. Alsoincluded are an intermediate tract of arterial line 33 which fluidlyconnects an arterial outlet of the first module A (connected to anoutlet of the blood pump tube tract) with an arterial inlet of thesecond module B (connected to the blood inlet of the post-pump arterialexpansion chamber), and an intermediate tract of venous line 34 whichfluidly connects a venous outlet of the second module B (connected withthe post-dilution branch 26) with a venous inlet of the first module A(connected with an inlet of the venous expansion chamber).

The second module B comprises a support element to which the supply lineof the replacement fluid 23 is constrained in order that thepre-dilution 25 and post-dilution branches 25 and 26 are positioned in aprefixed position with respect to the post-pump arterial expansionchamber. The correct and stable positioning of the pre-dilution andpost-dilution branches 25 and 26 with respect to the front panel of thedialysis machine enables operatively efficient use of the above-saidbranches with two control valves, a pre-dilution control valve 52 and apost-dilution control valve 53 arranged on the front panel.

The support element comprises, in the present embodiment, one or moreextensions 35 which emerge from the expansion chamber which bears thereplacement fluid pump tube tract 29 (i.e. the post-pump arterialchamber 12). The extensions 35 emerge from a side of the chamber 12located on the opposite side with respect to the replacement fluid pumptube tract 29 and extend in an opposite direction with respect to theextension of the pump tract 29 itself. The extensions 35, in the presentembodiment, are rigidly connected to the chamber 12 that bears thereplacement fluid pump tube tract 29. The extensions 35, in the presentembodiment, are made (for example by press-forming of plastic material)in a single piece with the chamber 12 itself. The support elementfurther comprises a casing 36 engaged to one or more of the extensions35. The casing 36 in the present embodiment is joint-coupled to one ormore of the extensions 35. In particular the casing 36 is coupled to oneor more of the extensions 35 in at least two joint zones. The casing 36,made of plastic material, is provided with a front part which at leastpartially contains the tubular body of the ultrafilter 28.

One of the extensions 35 exhibits a mounting extension 37 which, incollaboration with the two tubular extensions 38 for engagement of theends of the replacement fluid pump tube tract 29, serve for removablymounting the second module B on the front panel of the dialysis machine.

The pre-dilution 25 and post-dilution 26 branches each comprise at leasta tract of flexible tube which can be obstructed by squeezing. Thesetracts of flexible tube are positioned in a prefixed position withrespect to the post-pump arterial expansion chamber 12. The correctpositioning of the prefixed position is easily reached when mounting themodule B on the front panel of the machine, by virtue of the fact thatthe fluid connection system formed by the second flexible tube 44 andthe third flexible tube 45 are positioned stably with respect to thesupport element of module B, so that the pre-dilution 25 andpost-dilution 26 branches (made from the third flexible tube 45) areimmobile with respect to the support element of module B, although eachof them is elastically deformable and therefore closable by squeezing ofthe valves 52 and 53.

The branch from the pre-dilution 25 and post-dilution 26 branches whichis not fluidly connected to the expansion chamber bearing thereplacement fluid pump tube tract 29 can be constrained, directly or viaa tract of the extracorporeal blood circuit, to the support element. Inthe present embodiment, in which the expansion chamber bearing thereplacement fluid pump tube tract 29 is the post-pump expansion chamber12 (which chamber 12 is connected to the pre-dilution branch 25), thepost-dilution branch 26 can be constrained to the support element via atract of venous line 7 of the extracorporeal blood circuit. Inparticular, a tract of venous line 7 is engaged in two recesses affordedin the casing 36, and the post-dilution branch 26 is fluidly connectedto this tract of venous line 7.

The main branch 24 of the supply line 23 is constrained (for exampledirectly, as in the present embodiment) to the support element. Inparticular the main branch 24 exhibits at least a support zone thatinteracts (in a gripping and/or direct contact coupling) with thesupport element in a tract to that is downstream of the ultrafilter 28.In more detail, a tract of the main branch 24 arranged downstream of theultrafilter 28 is engaged (by, for example, a removable joint) in aseating afforded on one of the extensions 35. This tract of the mainbranch 24 (which in the present embodiment is part of the secondflexible tube 44) exhibits, at the ends thereof, two annular projectionswhich are axially distanced from one another and which are arrangedexternally of the opposite ends of the seating 46, functioning as stablecentring and positioning tabs of the tract of main branch 24 in theseating 46.

The ultrafilter 28 is supportedly constrained to the support element ofmodule B, in particular to the casing 36.

The support element can realise at least a mechanical and not fluidinterconnection between the expansion chamber bearing the replacementfluid pump tube tract 29 (i.e. the chamber 12) and the replacement fluidsupply line 23 and/or between the expansion chamber bearing thereplacement fluid pump tube tract 29 (chamber 12) and the extracorporealblood circuit. A mechanical and not fluid interconnection can also beoperating between the expansion chamber 12 and the venous line 7 (or thepost-dilution branch 26 or, respectively, the arterial line 6 (or thepre-dilution branch 25).

One of these mechanical and not fluid interconnections comprises, in thepresent embodiment, one of the extensions 35 in the form of an arm thatemerges (on the opposite side with respect to the replacement fluid pumptube tract 29) from the expansion chamber 12 which bears the replacementfluid pump tube tract. As already mentioned, this arm exhibits at an endthereof an attachment point (seating 46) for the main branch 24 of thesupply line 23. As already mentioned, the support element realises boththe mechanical and not fluid interconnection between the chamber 12 andthe line 23, and the mechanical and not fluid interconnection betweenthe chamber 12 and the blood circuit.

The support element of the second module B comprises, in the presentembodiment, two elements which are assembled one to the other, i.e. theextensions 35 (integrated with the chamber 12) and the protection casing36. However it would be possible, in further embodiments of theinvention, to have the support element made in an integrated singlepiece or an assembly of three or more distinct elements.

The second module B comprises an integrated element which defines theexpansion chamber supporting the replacement fluid pump tube is tract29, i.e. the chamber 12. This integrated element also defines a part ofthe support element of the second module B, in particular the extensions35.

The integrated element further defines a first conduit 39 for bloodinlet into the expansion chamber 12, a second conduit 50 for replacementfluid inlet, and a third conduit 40 for blood outlet (or blood mixedwith replacement fluid) from the expansion chamber 12.

The first and third blood conduit 39 and 40 belong to the extracorporealblood circuit and are located on two opposite sides of theabove-described expansion chamber 12 and extend in length in a verticaldirection, with reference to an operative configuration in which thepump tube tract 29 is coupled to the replacement fluid circulation pump30.

The first and third blood conduits 39, 40 also each have a bottom endwhich is fluidly connected to an expansion reservoir 47 of the post-pumparterial expansion chamber 12, and an upper end which is fluidlyconnected (via the ports 20 and 22) to the rest of the arterial line 6,respectively before and after the post-pump arterial expansion chamber12. In particular the first inlet conduit 39 is connected to an initialpart of the arterial blood line 6 having the patient end 9 destined forconnection with the arterial vascular access; the third outlet conduit40 is connected to a final part of the arterial blood line 6 having thedevice end 13 destined for connection to the hemo(dia)filter 5.

With reference to figures from 7 to 14, the integrated element definingthe chamber 12 is described in greater detail. The chamber 12 comprisesthe expansion reservoir 47 which is provided with a bottom, a top, atleast a first side extending between the bottom and the top, a firstaccess 48 arranged on the first side at a distance from the bottom andtop, and a second access 49.

The first conduit 39 terminates in the first access 48. A second conduit50 terminates in the first conduit 39 or, as in the present embodiment,in the expansion reservoir 47. The first conduit 39 and the secondconduit 50 terminate in the first access 48 with, respectively, a firstflow direction and a is second flow direction which are incident to oneanother.

The first conduit 39 terminates in the first access 48 with a first flowdirection having at least a motion component directed towards thebottom. The first flow direction has at least a motion componentdirected towards a second side of the expansion reservoir 47; the secondside extends between the bottom and top and is opposite the first side.

The second conduit 50 terminates in the expansion reservoir 47 with asecond flow direction having at least a motion component directedtowards the second side of the expansion reservoir 47. The second flowdirection has at least a motion component directed towards the top. Thesecond flow direction has at least a first motion component that ishorizontal and directed towards the inside of the expansion reservoir47.

The second conduit 50 comprises an intermediate tract 59 having a flowdirection provided with at least a second horizontal motion componentgoing in an opposite direction to the first horizontal motion component.The flow direction of the intermediate tract 59 is provided with atleast a vertical motion component.

The first conduit 39 has a diverging tract 51 with a fluid passage thatbroadens in the direction of the first access 48. The diverging tract 51broadens towards the bottom of the reservoir 47. The expansion reservoir47 extends prevalently on a lie plane; the diverging tract 51 enlargesprevalently in a perpendicular direction to the lie plane. The divergingtract 51 terminates at the first access 48.

The first access 48 is elongate and extends in a perpendicular directionto the first side of the reservoir 47.

The second access 49 is arranged on the bottom of the reservoir 47. Thethird conduit 40 terminates in the second access 49. The third conduit40 extends in length by the side of the second side of the expansionreservoir 47.

The first conduit 39 terminates in the first access 48 with a first flowdirection directed towards the second access 49. The first flowdirection has at least a motion component which is direction towards thebottom.

The second conduit 50 terminates on the first side of the expansionreservoir 47 below the end of the first conduit 39. The second conduit50 terminates either in the first access 48 contiguously below the endof the first conduit 39 (as in the present embodiment), or, in a furtherembodiment, not illustrated, it terminates in an intermediate accessarranged between the first access 48 and the bottom of the reservoir 47.

The expansion reservoir 47 has an upper part, comprised between thefirst access 48 and the top, having a greater width than a lower partcomprised between the bottom and the first access 48.

The first conduit 39 meets the second conduit 50 in a connecting zone,and joins the connecting zone in a position above the second conduit 50.

The first conduit 39 extends lengthwise by the side of the first side ofthe reservoir 47. The first conduit 39 is designed to introduce thetransported flow (in the present embodiment the arterial blood) into theconnecting zone with at least one motion component directed in adownwards direction. The second conduit 50 is designed to introduce thetransported flow (in this case the replacement fluid) into theconnecting zone with at least a motion component directed upwards. Thefirst conduit 39 and the second conduit 50 are designed so that each ofthe respective transported flows is introduced into the connecting zonewith at least a horizontal motion component directed internally of theexpansion reservoir 47.

The first conduit 39 and the second conduit 50 are arranged on a sameside (the first side) of the expansion reservoir 47. The first conduit39 is situated above the second conduit 50.

The first side of the expansion reservoir 47 has an upper zone with avertical inclination, and a lower zone with an oblique inclination. Theoblique lower zone of the first side is inclined in a direction nearingthe second side. This oblique inclination determines a narrowing of theexpansion reservoir 47. The zone of the second side that is facing theoblique zone of the first side is substantially vertically oriented. Thefirst conduit 39 has an upper tract having a substantially verticallongitudinal axis, and a lower tract having an oblique longitudinalaxis. The oblique axis is inclined in a direction nearing the secondside of the expansion reservoir 47. The first conduit 39 terminates inthe expansion reservoir 47 with an oblique inclination.

The first conduit 39 is made in a single piece with the expansionreservoir 47. The second conduit 50 is made in a single piece with theexpansion reservoir 47. The third conduit 40 is made in a single piecewith the expansion reservoir 47. The chamber 12 is realised by assemblyof two half-shells. The two half-shells are obtained by press-forming ofa plastic material.

The extracorporeal blood line which includes the chamber 12 is, in thepresent embodiment, the arterial line 6. The chamber 12 can, however, beassociated (alternatively or in addition to the arterial line 6) to thevenous line 7. The chamber 12 in this case would be a mixing chamber forreplacement fluid (in post-dilution) for degassing and for monitoringpressure, arranged downstream of the hemo(dia)filter; the inlet port 20would be connected to the hemo(dia) filter 5, while the outlet port 22would be connected to the vascular access.

During treatment, in which the arterial line 6 and the venous line 7 areconnected to the patient, the blood pump 8 is activated, so that theblood is removed from the patient via the arterial line 6, is sent tothe hemo(dia)filter 5, and is returned to the patient via the venousline 7. The replacement fluid pump 30 is also activated, so that thedialysis fluid is removed from the on-line port 4 of the machine, ismade to pass first through the pump tube tract 29 and then theultrafilter 28, and is then sent selectively to the chamber 12 on thearterial line 6 (opening the pre-dilution valve 52 operating on thebranch 25 and closing the post-dilution valve 53 operating on the branch26) or to the venous line 7 (valve 52 closed and valve 53 open), or toboth (valves 52 and 53 both open).

In a case of pre-dilution, the replacement fluid flow enters theexpansion reservoir 47 from below, transversally encountering the bloodflow that enters the reservoir from above. Both flows are obliquelydirected, each with an inlet component into the expansion reservoir 47which is horizontally directed (with reference to the work position ofthe chamber 12) towards the second side of the expansion reservoir 47,and a vertical component having an opposite direction to the directionof the flow. The meeting of the two flows causes an effective remixingbetween the blood and the replacement fluid, so that the mixed liquid(blood and replacement fluid) that exits through the third conduit 40 ishomogeneously mixed.

The special conformation and arrangement of the chamber 12 enables bothan effective remixing of the blood and replacement fluid and aneffective degassing of the liquids entering the expansion reservoir 47,especially the replacement fluid, thus preventing any air bubblesexiting through the third conduit 40.

In the absence of pre-dilution (valve 52 closed), the replacement fluiddoes not reach the chamber 12, while the blood enters through the firstconduit 39 and exits through the third conduit 40; since the firstconduit 39 terminates directly facing the inlet of the third conduit 40,the turbulence created is relatively low, reducing to a minimum theformation of foam and flow resistors, while at the same time enablingseparation of the air which may still be present in the blood.

Before the treatment is performed the circuit is primed by connectingthe patient venous end 16 to the connector 31 and the patient arterialend 9 to a discharge (for example a collection bag or a dischargeconnected to the exhausted fluid circuit of the dialysis machine). Thenthe clamp 32 is opened, the valves 52 and 53 are closed, the pump 8 isactivated (with the tract 29 not coupled to the pump 30) in order toaspirate fluid from the port 4 and to circulate the fluid along thevenous line 7, the blood filter of the hemodiafilter 5, and the arterialline 6 up to the end 9. The priming of the post-dilution branch 26 isperformed by activating the pump 8, closing the venous clamp 18 andopening the valve 53 (with the valve 52 closed), while the priming ofthe pre-dilution branch 25 is done by opening the valve 52 (with thevenous clamp 18 and the valve 53 closed).

In a further embodiment (not shown) the support element comprises aselector configured to selectively squeeze the flexible tube tracts ofthe pre-dilution and post-dilution branches. The selector comprises amovable (e.g. rotatable) member mounted on (e.g. rotatably coupled to)the support element. The movable member includes a first end and asecond end and can assume at least two configurations. In a firstconfiguration the first end squeezes one of the flexible tube tracts andin a second configuration the second end squeezes the other of theflexible tube tracts.

LEGEND

-   -   1. Hemo(dia)filtration apparatus    -   2. Fresh dialyser fluid port    -   3. Exhausted fluid port    -   4. On-line port    -   5. Hemo(dia)filter    -   6. Arterial line    -   7. Venous line    -   8. Blood pump    -   9. Patient arterial end    -   10. Pre-pump arterial expansion chamber    -   11. Blood pump tube tract    -   12. Post-pump arterial expansion chamber    -   13. Arterial device end    -   14. Venous device end    -   15. Venous expansion chamber    -   16. Venous patient end    -   17. Arterial clamp    -   18. Venous clamp    -   19. Tubular extensions connected to the chamber 10 for        attachment of the blood pump tube tract 11    -   20. Blood inlet port of the post-pump arterial expansion chamber    -   21. Replacement fluid inlet port of the post-pump arterial        expansion chamber 12    -   22. Outlet port for blood(-replacement fluid) from post-pump        arterial expansion chamber 12    -   23. Replacement fluid supply line    -   24. Main branch of line 23    -   25. Pre-dilution branch of line 23    -   26. Post-dilution branch of line 23    -   27. Inlet end of line 23    -   28. Ultrafilter of replacement fluid    -   29. Replacement fluid pump tube tract    -   30. Replacement fluid pump    -   31. Auxiliary connection of line 23 (for priming)    -   32. Auxiliary connection 31 intercept clamp    -   33. Intermediate tract of arterial line between the two modules        of the hemodiafiltration apparatus    -   34. Intermediate tract of venous line between the two modules of        the hemodiafiltration apparatus    -   35. Support extensions emerging from the post-pump arterial        expansion chamber    -   36. Casing    -   37. Mounting extension    -   38. Tubular extensions for supporting the replacement fluid tube        tract    -   39. First conduit for blood inlet into the post-pump arterial        expansion chamber    -   40. Third blood outlet conduit of the post-pump arterial        expansion chamber    -   41. First flexible tube    -   42. First tubular connection    -   43. Second tubular connection    -   44. Second flexible tube    -   45. Third flexible tube    -   46. Seating predisposed on the support element for fixing the        main branch 24    -   47. Expansion reservoir    -   48. First access of reservoir 47    -   49. Second access of reservoir 47    -   50. Second inlet conduit of replacement fluid into the post-pump        arterial expansion chamber    -   51. Diverging tract of the first conduit 39    -   52. Pre-dilution control valve    -   53. Post-dilution control valve    -   54. Connection for service line located at top of expansion        reservoir 47    -   55. Connection for an ultrafilter vent line    -   56. Connection for the auxiliary line provided with the        auxiliary connector 31    -   57. Connection for an end of the initial tract of replacement        fluid line 23 having the inlet 27 at the opposite end    -   58. Device for detecting pressure in the blood chamber 12    -   59. Intermediate tract of second conduit 50

1-30. (canceled)
 31. An extracorporeal blood chamber, comprising: anexpansion reservoir provided with a bottom, a top, at least a first sideextending between the bottom and the top, a first access arranged onsaid first side at a distance from said bottom and said top, and asecond access; a first conduit terminating in said first access; asecond conduit terminating in said first conduit, or in said first sideof the expansion reservoir, or in said expansion reservoir.
 32. Thechamber of claim 31, wherein the first conduit and the second conduitterminate in the first access with, respectively, a first flow directionand a second flow direction which are incident to one another.
 33. Thechamber of claim 31, wherein the first conduit terminates in the firstaccess with a first flow direction having at least a motion componentdirected towards the bottom of the expansion reservoir.
 34. The chamberof claim 31, wherein the expansion reservoir has a second side oppositethe first side and extending between the bottom and the top of theexpansion reservoir, the first conduit terminating in the first accesswith a first flow direction having at least a motion component directedtowards said second side.
 35. The chamber of claim 31, wherein theexpansion reservoir has a second side opposite the first side andextending between the bottom and the top of the expansion reservoir, thesecond conduit terminating in the expansion reservoir with a second flowdirection having at least a motion component directed towards saidsecond side of the expansion reservoir.
 36. The chamber of claim 31,wherein the second conduit terminates in the expansion reservoir with asecond flow direction having at least a motion component directedtowards the top of the expansion reservoir.
 37. The chamber of claim 31,wherein: the second conduit terminates in the expansion reservoir with asecond flow direction having at least a first horizontal motioncomponent, with reference to a use configuration of the expansionreservoir in which the bottom and the top are arranged, respectively,inferiorly and superiorly; and the second conduit comprises anintermediate tract defining a flow direction including at least a secondhorizontal motion component going in a direction opposite the firsthorizontal motion component.
 38. The chamber of claim 37, wherein theflow direction of the intermediate tract includes at least a verticalmotion component.
 39. The chamber of claim 31, wherein the first conduithas a diverging tract having a fluid passage section which broadensmoving towards the first access.
 40. The chamber of claim 39, whereinthe diverging tract broadens moving towards the bottom of the expansionreservoir.
 41. The chamber of claim 39, wherein: the expansion reservoirhas a substantially flat configuration with front and rear faces; andthe diverging tract broadens in a direction perpendicular to said frontand rear faces.
 42. The chamber of claim 39, wherein the diverging tractterminates at the first access.
 43. The chamber of claim 31, wherein thefirst access is elongate and extends in a direction perpendicular to thefirst side.
 44. The chamber of claim 31, wherein the second access isarranged at the bottom of the expansion reservoir.
 45. The chamber ofclaim 31, wherein it comprises a third conduit terminating at the secondaccess.
 46. The chamber of claim 45, wherein the third conduit extendsalong a second side of the expansion reservoir located opposite thefirst side.
 47. The chamber of claim 31, wherein the first conduitterminates in the first access with a first flow direction directedtowards the second access.
 48. The chamber of claim 31, wherein thefirst conduit extends along the first side.
 49. The chamber of claim 31,wherein the first conduit terminates in the first access with a firstflow direction having at least a motion component directed towards thebottom of the expansion reservoir; the second conduit terminating on thefirst side of the expansion reservoir below the end of the firstconduit, with reference to a use configuration of the expansionreservoir in which the bottom and the top are arranged, respectively,inferiorly and superiorly.
 50. The chamber of claim 49, wherein thesecond conduit terminates either in the first access, contiguously belowthe end of the first conduit, or in an intermediate access arrangedbetween the first access and the bottom of the expansion reservoir. 51.The chamber of claim 31, wherein the expansion reservoir has an upperpart, comprised between the first access and the reservoir top, having agreater width than a lower part comprised between the reservoir bottomand the first access.
 52. The chamber of claim 31, wherein the firstconduit meets the second conduit in a mixing zone, reaching said mixingzone at a position located above the second conduit, where above isintended with reference to a use configuration of the expansionreservoir in which the bottom and the top are arranged, respectively,inferiorly and superiorly.
 53. The chamber of claim 52, wherein: thefirst conduit is designed to introduce the flow into the mixing zonewith at least a motion component directed downwards, with reference tothe use configuration of the expansion reservoir; and the second conduitis designed to introduce the flow into the mixing zone with at least amotion component directed from below in an upwards direction.
 54. Thechamber of claim 52, wherein the first conduit and the second conduitare designed so that each of the respective flows is introduced into themixing zone with at least a horizontal motion component directedinwardly of the expansion reservoir.